Question

我试图创建一个用户并插入到Access数据库中，但是当我单击按钮时出现错误“ connectionString属性尚未初始化”

我已经在连接字符串上尝试了所有可能的代码，但是挑战仍然存在。

Try
    Dim sqlconn As New OleDb.OleDbConnection
    Dim sqlquerry As New OleDb.OleDbCommand
    Dim connString As String

    connString = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=|DataDirectory|\PavilionDB.mdb"
    sqlquerry.Connection = sqlconn
    con = New OleDbConnection(conString)

    con.Open()
    Dim cmd As OleDbCommand = New OleDbCommand(sql, con)
    sqlquerry.CommandText = "INSERT INTO member(mmbr_id, name, gender, address, phone, join_date, acc_no) VALUES (@txtNewID, @txtName, @txtGender, @txtAddress, @txtPhone, @txtPhone, @)txtAccNo"
    sqlquerry.Parameters.AddWithValue("New ID", txtNewID.ToString)
    sqlquerry.Parameters.AddWithValue("Name", txtName.ToString)
    sqlquerry.Parameters.AddWithValue("Gender", txtGender.ToString)
    sqlquerry.Parameters.AddWithValue("Address", txtAddress.ToString)

    Dim da As New OleDbDataAdapter(cmd)
    Dim ds As New DataTable
    da = New OleDb.OleDbDataAdapter(sql, con)
    da.Fill(ds, "con")
    Return
    sqlquerry.ExecuteNonQuery()
    sqlconn.Close()

Catch ex As Exception
    MessageBox.Show(ex.Message)
End Try

Answer 1

该代码确实是一团糟。应该减少到这个数目，这样才能解决您的问题：

Try
    Using connection As New OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0;Data Source=|DataDirectory|\PavilionDB.mdb"),
          command As New OleDbCommand("INSERT INTO member (mmbr_id, name, gender, address, phone, join_date, acc_no) VALUES (@mmbr_id, @name, @gender, @address, @phone, @join_date, @acc_no)", connection)
        With command.Parameters
            .AddWithValue("@mmbr_id", txtNewID.Text)
            .AddWithValue("@name", txtName.Text)
            .AddWithValue("@gender", txtGender.Text)
            .AddWithValue("@address", txtAddress.Text)
            'Set other parameters here.
        End With

        connection.Open()
        command.ExecuteNonQuery()
    End Using
Catch ex As Exception
    MessageBox.Show(ex.Message)
End Try

理想情况下，您也会使用Add而不是AddWithValue，但这是另一回事。

Answer 2

这里的问题是您的代码中有2个命令，分别为cmd和sqlquerry。您可以在代码的开头定义sqlqeurry，然后使用连接和我无法确定其来源的sql变量初始化cmd。

您需要做的是重做这一部分，并删除似乎是问题根源的多余参考。请考虑以下...

Try
    Dim conString As String
    Dim text = "INSERT INTO member(mmbr_id, name, gender, address, phone, join_date, acc_no) VALUES (@txtNewID, @txtName, @txtGender, @txtAddress, @txtPhone, @txtPhone, @)txtAccNo"

    conString = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=|DataDirectory|\PavilionDB.mdb"
    Using sqlCon = New OleDbConnection(conString), sqlCmd = New OleDbCommand(text, sqlCon)
        With sqlCmd.Parameters
            .AddWithValue("New ID", 234234)
            .AddWithValue("Name", "Fabulous")
            .AddWithValue("Gender", "Male")
            .AddWithValue("Address", "127.0.0.1")
        End With

        sqlCon.Open()
        sqlCmd.ExecuteNonQuery()
    End Using
Catch ex As Exception
    MsgBox(ex.Message)
End Try

我无法确定txtNewID和其他类似命名的变量是否为文本框。如果它们是文本框，则需要.Text属性，该属性以字符串形式获取内容。您需要替换我在测试环境中使用的文字来实现它。

确保所有内容（包括连接字符串和查询）均正确无误，以便顺利运行。在当前情况下，由于尝试对未与该连接关联的连接执行查询，因此出现与连接字符串相关的错误。

Answer 3

除了此链接上的整个开放源代码之外，这里还有一些简单的代码可满足您的主要要求： enter link description here

这是经过测试的代码：

    Private Sub BtnAddNewRec_Click(sender As Object, e As EventArgs) Handles BtnAddNewRec.Click

    Dim con As New OleDbConnection
    Dim cmd As New OleDbCommand
    Try
        con.ConnectionString = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=|DataDirectory|\db1.mdb"
        con.Open()

        cmd.Connection = con
        cmd.CommandText = "INSERT INTO Tbl1 (mmbr_id, name, gender, address) VALUES (@txtNewID, @txtName, @txtGender, @txtAddress)"

        cmd.Parameters.AddWithValue("@txtNewID", txtNewID.Text)
        cmd.Parameters.AddWithValue("@txtName", txtName.Text)
        cmd.Parameters.AddWithValue("@txtGender", txtGender.Text)
        cmd.Parameters.AddWithValue("@txtAddress", txtAddress.Text)
        cmd.ExecuteNonQuery()

        MsgBox("Record Added Successfully!")

    Catch ex As Exception
        MessageBox.Show("Error while inserting record on table..." & ex.Message, "Insert Records")
    Finally
        con.Close()
    End Try

End Sub

我希望这会有所帮助：

如何修复connectionstring属性尚未初始化

3 个答案: